This present disclosure is related to the treatment of subterranean production intervals and, more particularly, to a reverse-out valve that minimizes swabbing of the formation caused by service tool manipulations during the well treatment operation.
In the oil and gas industry, particulate materials such as sand and other wellbore debris are often produced to the surface during the extraction of hydrocarbons from a well traversing unconsolidated or loosely consolidated subterranean formations. Producing such particulate matter can cause abrasive wear to components within the well, such as tubing, pumps, and valves, and can sometimes partially or fully clog the well creating the need for an expensive workover operation. Also, if the particulate matter is produced to the surface, it must be removed from the extracted hydrocarbons by various processing equipment at the surface.
In order to prevent the production of such particulate material to the surface, unconsolidated or loosely consolidated production intervals in the well are often gravel packed. In a typical gravel pack completion, a completion string including a packer, a circulation valve, a fluid loss control device and one or more sand control screens, is lowered into the wellbore to a position proximate the desired production interval. A service tool is then positioned within the completion string and a fluid slurry that includes a liquid carrier and a particulate material (i.e., gravel) is then pumped through the circulation valve and into the well annulus formed between the sand control screens and the perforated well casing or open hole production zone. The liquid carrier either flows into the adjacent formation or returns to the surface by flowing through the sand control screens, or both. In either case, the gravel is deposited around the sand control screens to form a gravel pack, which is highly permeable to the flow of hydrocarbon fluids but simultaneously blocks the flow of the particulate material often carried in the hydrocarbon fluids. As such, gravel packs can successfully prevent the problems associated with the production of particulate materials from the formation.
During gravel packing operations, the service tool used to deliver the gravel slurry must be operated between various positions. For example, the service tool typically has a run-in configuration, a gravel slurry pumping configuration and a reverse-out configuration. In order to operate the service tool between these positions, the service tool is axially manipulated relative to the completion string. In addition, the service tool is often used to open and close the circulation valve, which also requires the axial movement of the service tool relative to the completion string. Such axial movement of the service tool, however, can adversely affect the surrounding formation. For instance, movement of the service tool uphole relative to the completion string can undesirably draw production fluids out of the formation, and movement of the service tool downhole can undesirably force wellbore fluids into the formation. This type of swabbing can damage the formation, including causing damage to the filter cake in an open hole completion.
To avoid detrimental swabbing of the wellbore, some tools use a weep tube to move the service tool string. The weep tube allows a controlled rate of fluid to transfer through the service tool and thereby maintain hydrostatic pressure on the surrounding formation. While weep tubes work well for reducing tool movement, weep tubes can also undesirably fracture the surrounding formation during reverse-out operations.